


sans oversleeps and goes to a lab.

by ratworm



Category: Undertale (Video Game)
Genre: Happy Ending, M/M, Post-Undertale Pacifist Route, W. D. Gaster is not related to Skelebros, sans PLEASE talk to people about shit im begging, this could be read as platonic but it's A Bit Gay
Language: English
Status: Completed
Published: 2019-02-26
Updated: 2019-02-26
Packaged: 2019-11-06 03:55:07
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,243
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17932376
Author URL: https://archiveofourown.org/users/ratworm/pseuds/ratworm
Summary: sans oversleeps and goes to a lab.(Alphys' lab. Where she's made an interesting machine with some interesting research- something about 'void' and the CORE?)





	sans oversleeps and goes to a lab.

**Author's Note:**

> ok so i saw one (1) sanster pic and my brain went **sad gay rights** and now we're here.
> 
> i havent written anything in possibly years (?) so idk how good this is but oof. hope u enjoy. 
> 
> rated teen for swearing lol bc that's just how it be im afraid
> 
> (italic text is either sans' thoughts or emphasis. you can guess which is which. go ham.)

Sans lay in his bed. 2pm. He'd woken up an hour ago, but hadn't felt like getting up. Papyrus had woken him at around 9 to tell him that he was going out for the day with Undyne and that he'd be back around 3, telling him to take care, that there was spaghetti in the fridge, to get out of bed before noon, etc, etc. (Sans appreciated it, he really did- he didn't know where he'd be without his brother. But god. Sometimes- sometimes it's all so _tiring._ )

He'd gone back to sleep after Paps had told him that. Eh. He'd get out of bed later. Maybe.

2:30pm. Sans rolls onto his front.

3pm. Sans falls back to sleep.

3:20pm. Sans rolls onto his back again.

4pm. Sans has a dream about ketchup and ducks and a field (and a fluid, cloying darkness, that chills you to the bones (ha ha) and numbs you to the world.)

4:30pm. Sans has another dream. This ones about exploring a jungle. There's nothing very special about it.

5:12pm. Sans wakes up. He lays there for a while, basking in the warmth of his bed. Then he stretches, reaching for his phone on the bedstand and turning it on with bleary eyes to see the display. 

_oh shit_ he thinks, seeing the time.

"hey paps, you home?" he calls out. Nothing.

 _oh shit_ he thinks again, typing out a 'paps, where r u?' and sending the text.

He sighs, sitting up and swinging his legs off the bed. He doesn't bother changing out of his pyjamas, but he slips on his slippers. 

He grabs his phone, absently scrolling through Undernet as he walks down the stairs, going into the kitchen to heat papyrus' spaghetti in the microwave.

He wasn't terribly worried about Papyrus- Undyne's always a bit wild with her plans- but he'd prefer a text all the same. Maybe he is a bit paranoid. Just a tad.

After finishing his spaghetti, he sits at the table for a while, checking his phone for notifications. There isn't much, just some stuff from groupchats he never talks in, and a couple trending posts his phone thinks he'd like. 

It'd been twenty minutes without a reply from Papyrus who was normally the epitome of responding quickly (unlike himself, who'd ignore messages out of laziness. A bad habit sure, but god damn is it the easy way out of socialising and being a functioning person), so Aans pressed the green call button on his phone, and waited for a response.

He picked up on the second ring, as usual. He breathed (but not really breathed) a sigh of relief.

"hey paps, sorry for calling."

"IT'S ALRIGHT, BROTHER! SORRY I DIDN'T RESPOND TO YOUR TEXT, I'M LATE BACK BECAUSE WE'RE AT ALPHYS' LAB, SHE'S DOING A COOL EXPERIMENTY THING!" 

"oh nice. and don't worry, i was just checking up on ya- you're so late you nearly gave me a _heart_ attack, and i don't even have one," 

"SANS!!!!!!!!!!!!" Papyrus shouted down the phone, somehow enunciating exactly twelve (12) exclamation marks in his speech. 

"ha, what's alphys doing though?" 

"OH! I SHOULD PROBABLY PASS THE PHONE OVER TO HER, SHE'LL EXPLAIN IT MUCH BETTER. IT'S SOMETHING ABOUT ACCIDENTS IN THE CORE?" 

Sans' breath hitched. Luckily, papyrus didn't seem to have noticed, as the shuffle of hands indicated he was indeed passing the phone over.

"h-hi Sans, yeah, I’m uh, doing runs on this machine I made. um, according to the maintenance records in the CORE, people have been going missing, but we can't, uh, remember them?" Sans gripped the phone a little harder. If he had skin, it'd be pulled taut over white knuckles. "but according to our scans, there's still somehow signs of life from them in the-"

"what," whispered sans, his voice as brittle as bone. _i always thought that, maybe, i could save him, maybe, just maybe, but... this... is it real?_

"y-yeah, it's, uh, really weird. I found this research and blueprints in one of the old bookshelves about some stuff relating to it and this thing called, uh, the void? I've used the information I've found to create this machine."

 _we made that research,_ Sans thought, brain on a numb overdrive from what Alphys was saying.

"so we've made this, uh, machine to retrieve them. we've been able to save quite a few so far- we have the records to confirm who we've got, and we're actually on the last recorded one now. we don't think there wouldn't be any others from the areas without railing, so, uh, yeah, we're almost done, so-"

"you're at your lab, yeah?" Sans said, voice somehow monotone over the tumultuous maelstrom of emotions raging in his soul.

"y-yeah, uh, sans, wh-"

He hung up. Flung on his jacket from where it was laying on the sofa. Went through a 'shortcut.'

 _i'm gonna get you back, gaster._  


* * *

He stumbles out of the shortcut, finding himself in the spacious room used for most of Alphys' experiments. (Now they were on the surface, Alphys mostly worked with robotics, computers, and implementing clean energy for the humans using technology from the CORE. She loved it.)

In the centre of the room is a large machine with some kind of capsule, big enough to fit a monster just over Papyrus' size. Alphys is standing in front of its control panel, jittery but with a straightness in her spine that showed her inner determination.

His eyes dart around the room- there stood Undyne, Alphys, and Papyrus, and he could see the figure of someone (possibly Toriel?) through the doorway in the room adjacent. They looked as though they were comforting or healing someone- most likely someone who had been saved from the CORE, Sans supposed.

"BROTHER!" Papyrus exclaims upon seeing him, "WHY ARE YOU- ARE YOU OKAY?" he asks worriedly, seeing Sans' panicked eyes and shaking hands.

"y-yeah, uh, hey," Sans stutters out, his gaze fixed on the machine. It looked so foreign, yet he could easily understand the interface and all the data shown upon it. 

"oh, h-hey Sans!" Alphys said, somehow unfazed by the sudden appearance of the small skeleton. "I’m just doing the last retrievaly-thing, oh, actually- it should work just about... _now_."

A bright light glowed inside the capsule, morphing and warping twisting into a form, a being- and then the light dimmed, leaving only some kind of bipedal lizard monster in its wake.

The others rushed forward to help them out of the machine, but Sans could only stand there, dumbstruck. 

Papyrus and Undyne helped calm the monster as Alphys turned off the machine. They all walked through to the next room, Papyrus gently patting him on the shoulder as they passed, recognising how his brother looked when distressed.

Sans could only stare at the machine.

He was alone in the room, now. 

Hesitantly, he took a step forward. And another. And another. He was standing in front of the control panel. Dials and buttons and screens covered the interface, but it was pretty simple for someone who'd been behind creating the entire theory for it. 

He reached a hand out towards the input slowly. It required a date of disappearance- no trouble for him. He'd had that date ingrained into his memory for years now.

He pressed in the digits. Confirmed his input. Placed a hand softly over the power button.

 _this is it._

* * *

The glow began again in the capsule. 

He was so nervous but so, so excited. 

He heard then gentle click of the door handle.

_huh. maybe i shoulda thought this through better._

"S-Sans, what are you-"

"Hey punk, get away from that machine!"

"BROTHER, WHAT ARE-?"

"it's okay, i know what i'm doing," Sans replied, still focused on the machine and the feedback it gave. 

"n-no you don't Sans, this- this is dangerous!" Alphys cried out, now running up to the control panel with him. He blocked it from her with his body.

"i've got it under control!" he yelled back, shoving her out of the way with his shoulder.

"Oi!" Undyne shouted, running forwards to ALphys, "don't try any fucking funny business!"

"Undyne, i-it's okay, I'm fine, I just-"

"Alphys..." Sans said in a soft voice, "do you remember the previous royal scientist?"

A pause.

"i- there was no- i don't think-"

"yeah," sans sighed, "exactly."

His eye burst blue as he swiftly raised his arm, creating a wall of bones between him and his friends. 

He turned back to the machine. He didn't have time to waste like this. Everything _seemed_ to be running smoothly, but something was wrong- the steady increase indicated by the brightening glow inside the capsule, had plateaued. He swore under his breath, quickly checking the other diagnostics, but there was nothing.

 _why would is it-? is it because it was so long ago that he disappeared?_ Sans thought, _i mean, the longer they'd been in the void, then the more energy would be need to reach in that far to get them. so does it need more energy? it takes a lot of magic to teleport, and that uses the properties of the void we'd studied, so would this be the same case, with it soaking up magic like a sponge?_

"alphys, when did the last person you retrieved disappear?"

"uh, around three years ago? S-Sans, are you trying to-?"

_that's way less than him, so maybe there isn't enough magic?_

"BROTHER, PLEASE CALM DOWN AND STOP THIS! MISS ALPHYS IS RIGHT, IT'S DANGEROUS!"

"don't worry bro, it's not," Sans said, waving a hand at him, going back to the machine. His skeletal hands skittered over the keyboard, trying to turn up the power.

"y-yes it is Sans! you don't know what you're doing-"

"i goddamn know what i’m doing, i made the fucking research in the first place!" sans yelled back, tired of this. He didn't want to argue. He just wanted him back.

"S-Sans- were you a scientist or something? h-how-"

Alphys was interrupted by a loud screeching sound from the machine.

_shit._

"okay so, uh," Sans began, crouching down to look at the underside of the machine. He quickly pried off the metal casing, revealing the wires and components beneath. "maybe this is a little dangerous, but uh, fuck it, i guess?”

He shrugged, reaching both hands inside to grasp the wires connected to the power inlet.

"S-Sans, don't-!"  
"Stop!"  
"BROTHER, NO!"

 _wow i really am an idiot, huh?_ Sans thought, pumping his magic into the wires. It stung his hands and created sparks, but he persevered, looking into the capsule with hope in his eyes.

Brighter, brighter, yet brighter.

The light increased, becoming a glaring, blinding thing that sans could barely stand to look at, but he forced himself to, he needed to see it work, it _had_ to work, he needed to see him again-

The light dimmed.

The room seemed dark as night when compared to the brilliance that was the shine of the capsule.

Sans couldn't breathe.

_did it work?_

He scrambled up, dizzy from the exertion of using so much magic. His hands grappled with the capsule, trying to claw it open with the desperation of a dying man.

It opened with a click, and he hastily yanked it open, looking into the darkness inside- that was pierced by a pale face, cracked and warped but so, so familiar. 

It felt as though time had stopped, leaving only him, and the man he'd missed for so long.

"gaster?" Sans choked out, hands shaking.

"S̨a̛ns̴,” the figure said, in that strange but so specific voice that could only be *him*, so recognisable despite the scratchiness born from years of disuse.

Sans felt the world around him crash into focus, as he rushed towards Gaster's strange, dark form, wrapping his arms tightly around the other like an anchor.

"i've missed you so much dings," Sans muttered, breaths shallow, "shit, you fucking idiot, you should've been more careful, god, i fucking love you, never go away again, please-"

"I ̢wo͘n'̨t."

There was silence as they held each other. Warmth.

And then, the moment was broken.

"Hey Sans," Undyne began, seemingly the only person brave enough to say anything, "What the fuck?"

Gaster snorted quietly, as if he couldn't help it, as Sans let go of him to turn to the others. He kept a hand on Gaster's arm, which then slid down into the other's hand in a gentle, but secure grasp.

Sans wore a grin as bright as the sun when he faced his friends, lowering his arm to dispel the bones he'd summoned in the heat of the earlier, uh, 'confrontation.'

"sorry for all the shit earlier, but uh," Sans stepped sideways, letting the others have a full view of the man in the capsule, "so… this is gaster."

The effect seemed instantaneous, recognition sparking in his friends eyes. Gaster waved to them, as they rushed forwards to get a better look at him.

They all fussed over him for a few minutes, with greetings and memories of his time with Alphys in the labs, meeting Papyrus and Undyne with Sans, his achievements- there was so much.

Sans’ hand didn’t leave Gaster’s for hours. (Even when he said he had to have a ‘time out’, laid down on the floor, and passed out because he’d used too much magic.) 

Gaster was back.

He felt like he was home.

**Author's Note:**

> thanks for reading!!
> 
> i have an undertale (mostly sanster) sideblog called [mrsansundertale](https://mrsansundertale.tumblr.com/) so come talk to me about shit!!
> 
> tell me if you enjoyed it or have any prompts/ideas for fics!! i wanna write more sanster but i have two braincells and cant think of anything sjhsdjsdf. also i have like,, 3k of another sanster fic written so yeehaw


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